Burner construction having casing with tangentially arranged air inlet and swirl chambers



J. P. KEATING 3,240,433 BURNER CONSTRUCTION HAVING CASING WITHTANGENTIALLY March 15, 1966 ARRANGED AIR INLET AND SWIRL CHAMBERS 2Sheets-Sheet 1 Filed April 8, 1963 INVENTOR' JAMES P. KEA 7'//v6 March15, 1966 J. P. KEATING 3,240,433

BURNER CONSTRUCTION HAVING CASING WITH TANGENTIALLY ARRANGED AIR INLETAND SWIRL CHAMBERS Filed April 8, 1963 2 Sheets-Sheet 2 INVENTOR.

JAMES 1 K154 TING ATTOR Y United States Patent C) 3 240,433 BURNERCONSTRUCT ION HAVING CASING WITH TANGENTIALLY ARRANGED AIR INLET ANDSWIRL CHAMBERS James P. Keating, Rockford, Ill., assignor to EclipseFuel Engineering Co., Rockford, 111., a corporation of Illinois FiledApr. 8, 1963, Ser. No. 271,309 1 Claim. (Cl. 239-400) The presentinvention relates to burners and has particular reference to a burnercasing construction which, by the simple expedient of nozzlesubstitution, is capable of use either as a gas burner or as a liquidfuel burner. Whether employed as a gas or liquid fuel burner, the burnercasing of the present invention is admirably well adapted for use inconnection with the internal heating of small diameter radiant tubes andin one illustration thereof, it is shown as being provided with agas-burning nozzle and in operative association with such a tube. Theburner casing is, however, suitable for use in firing a combustionblock, and in another illustration thereof, it is shown as beingprovided with a liquid fuel-burning nozzle and in operative associationwith a combustion block. It will be distinctly understood, however, thatthe casing may be employed for tube-heating purposes when equipped witha liquid fuel-burning nozzle and that it may similarly be employed forcombustion blockhea'ting purposes when equipped with a gas-burningnozzle. Irrespective, therefore, of the particular type of nozzleemployed, the fuel involved or the use to which the burner casing may beput, the essential features of the invention are at all times preserved.

Inasmuch as the principles of fuel and air introduction into the burnercasing, of fuel and air conduction and distribution through the casing,of fuel mixture at the outlet region of the casing, of flameestablishment, and of flame conduction and distribution in a directionforwardly of the burner casing remain substantially the same whether thefuel involved be fuel gas or a liquid will be discussed in detail hereinon the basis of a gas burner used for tube-firing purposes. Thereafter,when a full understanding of the principles involved has been had, theburner casing will be briefly described in association with a liquidfuel-burning nozzle with the burner as a whole being employed forcombustion block-firing purposes.

A conventional present-day gas burner which is designed for the samepurpose as the burner of the present invention is possessed of numerouslimitations, principal among which is the inability of such a burner totransfer the heat that is generated thereby to the wall of a tubeundergoing heating in proportion to the B.t.u. input of the burner. Thislimitation is attributed to lack of turbulence at the burner nozzle andaxially along the tube undergoing heating. Without such turbulence, thegenerated heat of the burner flame travels centrally along the tube andis insulated from the tube wall by a layer of relatively cool gaseswhich travel along the wall and hug the same for appreciably longdistances from the burner. At regions close to the burner nozzle, beforethese cool gases assume their encompassing position, there is a tendencyfor overheating.

Efforts to overcome the above-noted limitation of localized overheatingnear the burner and insuflicient heating at points remote from theburner have not proven altogether satisfactory. These efforts have beenpredicated upon attempts to secure increased turbulence within the tube,as, for example, the creation of obstructions in the path of gas flow,by corru-gating or dimpling the tube wall, or by the use of ceramictargets in the path of gas flow, not only to break up the even flow ofgases, but also to create radiant heat for direct application to thetube wall. Not only are such expedients costly from .a manufacturing andservicing standpoint, because they involve tube modification or internalsupport within the tube, but the uniformity of the attained heat leavesmuch to be desired inasmuch as the amount of turbulence established forany given obstruction varies in proportion to its distance from theburner.

The present invention is designed to overcome the above-noted limitationthat.is attendant upon the construction and use of a conventionalpresent-day radiant tube heating burner and, accordingly, the inventioncontemplates the provision of an extremely simple nozzlemixing burnerwhich requires no modification whatsoever of the tube undergoing heatingor internally-mounted tube obstructions or baflles, yet which willestablish a high degree of turbulence within the tube, both. in thevicinity of the burner and at points remote therefrom. The provision ofsuch a burner constitutes one of the principal objects of the invention.

Another and equally important object of the invention is to provide atube heating nozzlefmixing burner of the type under consideration and inwhich uniform heating of the associated tube takes place throughout anappreciably long longitudinal extent of the tube wall.

The provision of a burner which is comprised of but two principal parts,namely, a burner casing and a gas nozzle, and, therefore, may bemanufactured of a relatively low cos-t; one which is rugged and durableand has no intricate parts and, therefore, is possessed of acomparatively long life without requiring servicing; one which iscomparatively smooth and silent in its operation whether the same beused for tube or combustion block firing; one which requires no manualadjustment; and one which, otherwise, is well-adapted to perform theservices required of it, are further desirable features which have beenborne in mind in the production and development of the presentinvention.

In the accompanying two sheets of drawings forming a part of thisspecification, one illustrative embodiment of the invention has beenshown. i

In these drawings:

FIG. 1 is a sectional view taken substantially centrally andlongitudinally through a gas burner that is constructed according to thepresent invention and showing the same in operative association with atube undergoing firing;

FIG. 2 is a sectional view taken on the line 2-2 of FIG. 1 and in thedirection indicated by the arrows;

FIG. 3 is a sectional view taken on the line 3-3 of FIG. 1 and in thedirection indicated by the arrows; and FIG. 4 is a sectional viewsimilar to FIG. 1 but showlng a liquid fuel burner that is constructedaccording to the invention, the burner being in operative associationwith a combustion block undergoing firing.

Referring now to the drawing in detail and in particular to FIGS. 1 to3, inclusive, the burner 10 that is illustrated therein is essentially anozzle-mixing gaseous fuel burner and comprises two parts, namely, aburner casing 12 and a gas nozzle 14. The burner casing 12 preferably isin the form of a casting, while the gas nozzle 14 is in the, form of ashort length of tube stock and is press-fitted into the casing in amanner that will be described presently.

The burner casing 12 is generally of tear-drop configuration intransverse cross section as shown in FIGS. 2 and 3, and includes spacedapart front and rear walls 16 and 18 of tear-drop design and aconnecting continuous or peripheral marginal wall 20 of relatively shortaxial extent.

The rear Wall 18 ,of the burner casing is provided with an inlet opening21 for one of the two gaseous constituents of combustion, preferablyair, and an inlet opening 22 for the other gaseous constituent,preferably fuel gas. The air inlet opening 21 is established by reasonof an integral attachment flange 24 which threadedly receives one end ofan air supply conduit 26. The gas inlet opening 22 similarly isestablished by reason of an integral attachment flange 28 whichthreadedly receives one end of a gas supply conduit 30. The front wall16 of the casing 12 is provided with an air discharge opening 32. Thelatter is surrounded by an integral cylindrical flange 34 whichconstitutes the burner discharge nozzle. The air inlet opening and theair discharge opening 32 are of approximately the same diameter, whilethe diameter of the gas inlet opening 22 is reduced.

As best seen in FIGS. 2 and 3, the peripheral wall 20 of the burnercasing 12 is provided with a relatively large diameter, semi-cylindricalend wall section 40, a relatively small diameter, semi-cylindrical endwall section 42, and two generally tangential interconnecting side wallsections 44 and 46. The side wall section 44 is substantially flat anadmerges gradually with the end wall sections 40 and 42, while the sidewall section 46 is provided with an inwardly bowed portion 48. Aninwardly extending curved vane 50 is formed on the inwardly bowedportion 48 and constitutes a continuation of the curvature of thecylindrical end wall section 40 of the casing. The curved vane 50divides the interior of the easing into a relatively large swirl chamber52 and a relatively small air inlet chamber 54, the two chambers beingin communication through a throat port 56 which exists by reason of thespacing of the extreme or distal edge 58 of the vane 50 from the sidewall section 44. The crosssectional area of the throat port 56 is atleast as great as the cross-sectional area of the air inlet opening 21,it being shown in the illustrated form of the invention as beingsomewhat larger than such air inlet opening so that air admitted to theair inlet chamber 54 will not be restricted in its flow to the chamber52. The character and disposition of the curved vane 50 are such that atangent plane atthe distal edge of the vane extends at a small angle tothe plane of the side wall section 44.

The gas inlet opening 22 is offset from the longitudinal axis of thegenerally cylindrical swirl chamber 52, the direction of offset beingsuch that the vane 50 extends between the air inlet opening 21 and thegas inlet opening 22. The air inlet opening 21 is substantially centered,with respect to the generally cylindrical confines of the air inletchamber 54. The short length of tube stock which forms or COl'lS'Eltutesthe gas nozzle 14 has one end thereof press-fitted as at 60 (see FIG. 1)in the forward end of the gas inlet opening 22, and the nozzle extendsforwardly across the swirl chamber 52 and terminates in coaxialrelationship within the medial region of the flange 34 which forms orconstitutes the burner discharge nozzle.

As shown in FIG. 1, in the operation of the above described burner 10,the front wall 16 is welded or otherwise secured as at 62 to theproximate end of a radiant tube, such as the tube T to be heated, and aring 64, which is comprised of a suitable heat-resistant ceramic orother material, is disposed between the wall of the tube T and thecylindrical flange 34. The forward end region of ring of material ispreferably flared outwardly in frusto-conical fashion as indicated at66, tapering to a thin edge 68 'where it merges with the tube wall.

When the burner is fired, the air which enters the burner casing 12through the air inlet opening 21 passes through the throat port 56 andis forced against the end wall sec-- tion 40 surroundingt'he swirlchamber 52 and is constrained to follow the curvature of this end wallsection due to the centrifugal force involved. The axis of the flange 34which forms the discharge, nozzle being offset as preyicusly glesg libcdfrom the center of curvature of the end wall 40, the centrifugal forcesinvolved as the air swirls inwardly toward the air discharge opening ininvolute fashion become increasingly greater so that the air isdischarged through the flange 34 in a stable or even manner. Statedotherwise, the air which passes outwardly across the rim of thedischarge opening 32 has the same velocity at all points along such rim.The resulting discharge of air from the discharge nozzle 34 which isformed by the high rotative velocity with practically no forwardvelocity other than that imparted to it by reason of the pressure ofback-up air emerging from the swirl chamber 52. This escaping air isthus caused closely to hug the frusto-conical wall surface 66 of theceramic material 64 with a large component of circumferential velocityand a small component of forward velocity.

As the air passes forwardly through the aforementioned burner dischargenozzle, gas is picked up from the forward rim of the gas nozzle 14 andis constrained to follow the swirling motion of the air. At this initialregion of gas entrainment within the burner discharge nozzle, themixture is incomplete and little or no combustion takes place. However,as the two gaseous fluids move forwardly and are thrown radiallyoutwardly into contact with the frusto-conical surface 66 of the ring64, the intermixture improves and a more thorough mixing takes place tosupport combustion. At a region just forwardly of the frusto-conicalsurface 66 substantially stoichiometric conditions obtain, and becauseof'the fact that during travel of the mixed gaseous fluids forwardlyalong an appreciable length of the tube .T, there is a tendency for thesame to hub the cylindrical wall of the tube and establish acontinuation of the initial rotating swirling velocity of the productsof combustion, thus yielding heat evenly to the tube wall for anappreciable distance forwardly. of the burner 10.

In FIG. 4, the burner that is illustrated is essentially a nozzle-mixingliquid fuel burner and comprises a burner casing 112 and a liquid fuelnozzle 114. The burner casing 112 is identical in every respect to theburner casing 12 described in connection with the gas burner 10 of FIGS.1 to 3, inclusive, and, therefore, to avoid needless repetition ofdescription, corresponding reference numerals but of a higher order havebeen applied to the corresponding parts as between FIGS. 1 and 4.

The liquid fuel nozzle 114 which has been substituted for the gas nozzle14 of FIG. 1 is in the form of a composite tube and a horizontallyextending liquid fuel tube 123. The composite tube embodies ahorizontally extending part the inner or forward end portion of whichextends through the swirl chamber 152 in the same manner as the nozzle14 extends through the swirl chamber 52 of the burner construction ofFIGS. 1 to 3, inclusive. The composite tube also comprises an externallydisposed, laterally extending or depending leg 115 through the upper endof which there projects in sealing relationship the liquid fuel tube123. Such liquid fuel tube extends longitudinally and centrally throughthe horizontal part of the composite tube of the nozzle 114 and itsforward end terminates at the forward end of the nozzle.

Liquid fuel is adapted to be supplied to the nozzle through the tube 123while gas (air) is adapted to be supplied to the nozzle through thelateral leg 115, the two constituents of combustion being dischargedinto the central regions of the cylindrical flange 134 which constitutesthe burner discharge nozzle. The gas is supplied under pressure so thatan atomizing effect on the liquid fuel takes place at the region of fueldischarge.

The burner casing 112 is shown as being operatively associated with acombustion block B which is installed within a furnace wall 125. Thecombustion block B is formed with the usual tapered combustion tunnel166 in register with the burner discharge nozzle 134.

The operation of the burner assembly 110 is substantially the same asthe operation of the burner assembly 10 so that a detailed descriptionthereof is unnecessary,

it being deemed sufficient to state that atomized liquid fuel and thegas within which it is entrained are introduced into the combustiontunnel at the base of the throat region thereof and combine with theswirling air issuing from the swirl chamber 152 in substantially thesame manner that the gas is combined with the air issuing from the swirlchamber 52 in the previously described burner 10. The swirling productsof combustion are thus carried a considerable distance forwardly of thecombustion block B where substantially stoichiometric conditions areprevalent.

The invention is not to be limited to the exact arrangement of partsshown in the accompanying drawings or described in this specification asvarious changes in the details of construction may be resorted towithout departing from the spirit or scope of the invention. Forexample, while the rear ends of the lengths of tube stock whichconstitute the fuel nozzles 14 and 114 are shown as being press-fittedinto the fuel inlet openings 22 and 122, respectively, obviously theparts may be threaded and thus connected together if desired. Such minordetails may be resorted to within the scope of the appended claim.

Having thus described the invention what I claim as new and desire tosecure by Letters Patent is:

A burner comprising, in combination, a unitary, vertically elongatedburner casing embodying a front wall, a rear wall, and a continuousperipheral wall extending between and connected to the front and rearwalls and consisting of a relatively large diameter, semi-cylindricalupper end Wall section, a relatively small diameter, semicylindricallower end wall section, a substantially straight first side wall sectionhaving its end regions connected to, and merging gradually andtangentially with, the adjacent end regions of the upper and lower endwall sections, and a second side wall section having its end regionsconnected to, and merging gradually and tangentially with, the adjacentend regions of said upper and lower end wall sections, and provided withan inwardly bowed central region, a curved vane disposed between andconnected to the central portions of the front and rear walls, havingone end thereof connected to the inwardly bowed central portion of thesecond side wall section, extending upwards and inwards at a small angleto the first side wall section and having its other end terminating asmall distance short of said first side wall section in order to formtherewith a throat port, said vane being curved complementally to theupper end wall section and having the upper side thereof defining withthe upper end wall section and the upper portions of the first andsecond side wall sections a comparatively large, substantially circular,free-flow, unrestricted swirl chamber, the lower side of said vaneforming with the lower end wall section and the lower portions of thefirst and second side wall sections a comparatively small free-flow,unrestricted air inlet chamber of pear shape in outline, said swirlchamber and said air inlet chamber being in communication with eachother through the throat port, the lower portion of the rear wall of thecasing being provided with a single central air inlet opening incommunication with the air inlet chamber and coaxially positioned withrespect to the lower end wall section, the upper portion of the casingfront wall being provided with an air discharge tube in communicationwith the swirl chamber, the upper portion of the casing rear wall beingprovided with a fuel inlet opening in axial alignment with the airdischarge tube, and a horizontally disposed tubular fuel nozzle havingits rear end sealingly connected to the fuel inlet opening, projectingacross the swirl chamber, and having its front end terminating withinsaid air discharge tube, said rear wall of the casing being imperforateexcept for said air inlet opening and said fuel inlet opening and thecasing front wall being imperforate except for the communication withsaid air discharge tube.

References Cited by the Examiner UNITED STATES PATENTS 2,215,272 9/1940OBrien 15876 2,433,317 12/1947 Carter 158-1.5 2,456,930 12/1948 DeLancey 15876 2,500,344 3/1950 Carter 15876 2,796,118 6/1957 Parker et al1269l 3,088,681 5/1963 McCutcheon 158-76 FOREIGN PATENTS 178,509 4/ 1922Great Britain.

FREDERICK L. MATTESON, JR., Primary Examiner.

MEYER PERLIN, JAMES W. WESTHAVER,

Examiners.

